Andrew Doyle/LONDON
THE EUROPEAN Commission is extending a key programme investigating the benefits of hybrid laminar-flow technologies for a further 12 months, after the original project showed that it could yield significant reductions in fuel consumption, while avoiding reliability problems.
Berhard Dziomba, the European Laminar Flow Investigation II (ELFIN II) project manager at Daimler-Benz Aerospace Airbus, which is coordinating the work, says that he is "optimistic" that laminarisation of the wing, engine nacelle and empennage will reduce an aircraft's fuel consumption by up to 20%. He adds that the problem of contaminants disrupting the smooth airflow can be overcome.
Dziomba is calling on manufacturers to embrace the technology, pointing out that laminar flow is already used on the Cessna Citation and Piaggio Avanti, while Dassault is flying a Falcon 900 business jet with hybrid laminar flow. "We need the systems people to face up to the needs of hybrid laminar flow," he says.
The ELFIN II project, which began three years ago and was scheduled to end in January, is being extended for another year to allow further wind tunnel testing and contamination protection work to be carried out. The 24 participants include Aerospatiale, Alenia, British Aerospace Airbus, Dassault Aviation, CASA, Rolls Royce and Snecma.
"We have very complex models and we wanted to make 100% sure that what we take to the wind tunnel works the way we designed it to," says Dziomba. "A lot of people are waiting for the data, and so we are proceeding carefully," he adds.
Critics of hybrid laminar flow claim that suction holes would rapidly become clogged and that leading edges would be contaminated by airborne particles, while suction systems would be too bulky and heavy for an aircraft's structure.
Dziomba claims that the ELFIN II work, as well as earlier projects such as one involving a Boeing 757 in 1990, has shown that contamination of suction holes is not a major concern. "It's not really a problem," he says. "We have knowledge that this has not occurred."
Insects can be encountered below 300ft (90m), however, and the project is investigating ways of keeping the holes clear.
One "feasible" proposal, says Dziomba, is to slowly pump a glycol solution through the holes "...creating a film which is hard for insects to penetrate". Flight through clouds, meanwhile, can have a "sandblasting" effect caused by the presence of ice particles.
To protect leading edges, anti-adhesive coatings are being developed, designed to prevent a build-up of contaminants.
Source: Flight International
